Drive unit for a hair cutting machine

ABSTRACT

A drive unit for a hair cutting machine comprises a driving motor that includes a substantially U-shaped stator which has a first leg, a second leg, and at least one additional leg located between the first leg and the second leg, at least one field coil which can be disposed on the at least one additional leg, and an armature. Lateral air gap sections are formed between the first and second leg and the armature while central air gap sections are formed between the additional leg and the armature. The central air gap sections and the lateral air gap sections extend at an angle from a longitudinal axis. A first nose, which faces away from the additional leg, is arranged at the end of the first leg, while a notch, which faces the additional leg and corresponds to the first nose, is arranged on the second leg.

The invention relates to a drive unit for a hair cutting machineaccording to the definition of the species in Patent Claim 1.

Such drive units are fundamentally known and include a stator, anexciter coil and an armature. The stator and the armature arestamp-packed from individual insulated sheet metal layers to preventeddy currents. The stator is designed to be essentially U-shaped and hasa first leg and a second leg, an additional leg being provided betweenthe first leg and the second leg. The exciter coil is designed as a coilfor an electromagnet and is usually positioned on the at least oneadditional leg. The armature is situated across the legs of the stator,lateral air gap sections being provided between the first leg and thearmature and between the second leg and the armature, and central airgap sections being provided between the additional leg and the armature.The central air gap sections and the lateral air gap sections run at aninclination relative to a longitudinal axis of the additional leg.

Such a drive unit is known from WO 00/27599 by the present applicant,for example.

One disadvantage with this design is that optimal mechanical performanceof the drive unit is not achieved. Another disadvantage is that withsuch a configuration, the copper consumption for the exciter coil andthe stamping waste of the dynamo sheet metal, of which the stator andarmature are packed, are relatively high.

The object of the invention is to improve upon a known drive unit for ahair cutting machine of the type defined in the introduction so that itwill no longer have the disadvantages described. In particular themechanical performance of the machine is to be improved, while at thesame time the copper consumption and the waste of dynamo sheet metal areto be reduced.

This object is achieved by a drive unit for a hair cutting machinehaving the feature of Patent Claim 1. Advantageous specific embodimentsare represented by the features of the subclaims.

A drive unit according to the invention for a hair cutting machine has adrive motor made of an essentially U-shaped stator having a first legand a second leg and at least one additional leg situated between thefirst leg and the second leg. The drive motor additionally has at leastone exciter coil, which may be situated on the at least one additionalleg. An armature is provided across the legs of the stator, lateral airgap sections being formed between the first leg and the armature andbetween the second leg and the armature, and central air gap sectionsbeing formed between the additional leg and the armature, these sectionsextending at an inclination with respect to a longitudinal axis of theadditional leg. An enlargement of a first lateral air gap sectionbetween the first leg and the armature is achieved by a first nose,which is situated on the end of the first end pointing away from theadditional leg. A notch provided on the second leg pointing to theadditional leg and corresponding to the nose achieves the effect that asecond air gap section between the first leg and the armature is notreduced in size and nevertheless a space-saving configuration ispossible in the stamped blank. Both the stator and the armature arestacked from individual insulated stamped plates, the individual layersbeing riveted, for example.

In a refinement of the invention, a second nose is provided on the endof the second leg pointing toward the additional leg. The second noseachieves the result that the second lateral air gap section between thesecond leg and the armature is also further increased in size. Thisspecific embodiment is advantageous in particular when the second leg isthe leg of the stator nearest a support of the armature, because smallerair gap fluctuations occur in the air gap section closer to the supportof the armature, and the air gap is designed to have a smaller gap widthon the whole.

To further improve the mechanical performance, it is advantageous if thearmature has a recess having an essentially triangular shape in the areaof the additional leg and if the recess has at least one section whichpoints toward the stator and runs parallel to the longitudinal axis ofthe additional leg. The additional leg is designed to be of a suitablelength so that in at least one section running parallel to itslongitudinal axis, it engages in the recess formed in the armature. Sucha design of the armature and the additional leg ensures that even duringoperation of the drive unit, the armature and additional leg permanentlycover each other, and thus the magnetic flux in this area is optimized.

The armature is advantageously connected to the stator or supportedtherewith in a vibration-capable mount via a spring bracket, which maybe placed on the second end of the armature. Alternatively, avibration-capable support of the armature may also be provided by afastening to an armature angle in a housing known from the prior art.However, the vibration-capable configuration of the armature on thestator via the spring bracket has the advantage that the drive unit maybe premounted outside of the housing and then mounted as a module in thehousing. The spring bracket may be attached to the armature and/or thestator by pressing it into a suitably shaped slot.

To optimize the magnetic flux, it is helpful if the stator has insideradii at transitions to the legs suitable for counteracting an excessiveincrease in the magnetic flux density in this area. Inside radii in thisconnection are understood to be rounded transitions which prevent alocal increase in the magnetic flux density.

To further optimize the consumption of material, it is advisable for theat least one additional leg to be designed thinner than the first andsecond legs. This measure makes it possible to achieve the same numberof coil windings with reduced consumption of copper wire or to implementan increased number of windings of the exciter coil with the sameconsumption of copper wire.

The exciter coil and the additional leg are ideally designed so that theadditional leg is operated approximately in magnetic saturation at agiven magnetic field strength. In this context, it is not advisable toexceed the saturation range because when operating in the saturationrange, increased field strength is achievable only by an extremelyelevated consumption of the product of current×windings.

For geometric optimization of the stamped blank, it is advisable in thiscontext if the stator has a recess between the first leg and the atleast one additional leg, so that an additional leg of a further statorplate engages in this recess in a stamped configuration. Through such aconfiguration, it is possible to design the additional leg to be longerand nevertheless allow the most compact possible configuration for thestamped blank.

In a refinement of the invention, two additional parallel legs areprovided with the stator. This specific embodiment has the advantagethat the width of the additional legs may be further reduced and theplacement of two exciter coils is possible.

A configuration of stamped profiles for a stator as described above ischaracterized in that two stator plates are rotated by 180°, theconfiguration being such that the first nose of the stator plate engagesin the notch on the other stator plate. This configuration permits aparticularly compact and waste-saving stamping of the individual statorplates.

A drive unit such as that described above is preferably used in a haircutting machine in particular.

The invention is explained in greater detail below with reference to theaccompanying figures.

FIG. 1 shows a top view of a first specific embodiment in which the unitincluding stator and exciter coil is separate from the armature,

FIG. 2 shows a top view of a configuration of stamped profiles for thestator from FIG. 1,

FIG. 3 shows a top view of a second specific embodiment in which thestator is designed to have two additional legs,

FIG. 4 shows a top view of a configuration of stamped profiles for thestator from FIG. 3, and

FIG. 5 shows a top view of a detail of the exemplary embodiment fromFIG. 1 in which the armature and the stator are connected by a springbracket.

Matching parts in the following detailed description of the figures arelabeled with the same reference numerals.

FIG. 1 shows a top view of a first exemplary embodiment of a drive unitaccording to the invention for a hair cutting machine having a drivemotor 1. Drive motor 1 is constructed of a stator 100 having an excitercoil 140 and an armature 150 situated in such a way that it correspondsto stator 100. Stator 100 is designed to be essentially U-shaped, havinga first leg 110 and a second leg 120. Exciter coil 140 sits on theperiphery of an additional leg 130 situated between first leg 110 andsecond leg 120. Armature 150 is situated across the ends of legs 110,120, 130 of stator 100, a tappet 160 being attached to first end 158 anda support 190 attached to second end 156. Tappet 160 has a suitabledesign for inducing vibration of a cutting set of a hair cutting machineand thus transmitting a movement of armature 150 to the cutting set.Support 190 is fastened by bolts 194, for example, in a housing and hasan oscillating spring 192, by which armature 150 is mounted to allowvibration.

To achieve the best possible mechanical performance of drive motor 1,various measures are implemented for optimization of drive motor 1.

In a first step, it is necessary to guide the magnetic flow within drivemotor 1 in the best possible manner and to generate the greatestpossible magnetically active air gap surfaces or air gap sections. Afirst air gap section A is formed between first leg 110 of stator 100and armature 150 and is increased in size toward the outside by theintegral molding of a nose 112. A second lateral air gap section Bformed between armature 150 and second leg 120 of stator 100 is alsoenlarged toward the outside by the integral molding of a second nose124. The increase in size of second air gap section B has a particularlygreat effect on the mechanical performance of drive motor 1 becausesecond air gap section B is closer to support 190 of armature 150 andtherefore the fluctuations in gap width s are smaller.

To allow the most space-saving possible configuration of stampedprofiles for stator 100 despite integrally molded first nose 112, anotch 122 is provided on second leg 120. However, the configuration ofthe stamped profiles is explained in greater detail with reference toFIG. 2.

A second approach to improving the mechanical performance of drive motor1 is to optimize an air gap between additional leg 130 and armature 150.Armature 150 therefore has a recess 152 in the area of additional leg130, designed essentially as a triangle having a section 154 runningparallel to a longitudinal axis of additional leg 130. Additional leg130 is also designed to be triangular at the end and engages in recess152 with its entire width. Thus central air gap sections a and b areformed between additional leg 130 and armature 150, running outwardrelative to longitudinal axis L and transitioning into air gap section crunning parallel to longitudinal axis L. Due to such an embodiment ofdrive motor 1, deeper engagement of additional leg 130 in recess 152 ofarmature 150 is achieved, so that a permanent vertical coverage ofadditional leg 130 and armature 150 is ensured even during operation ofdrive motor 1. Due to this vertical coverage in air gap sections crunning parallel to longitudinal axis L, an improved magnetic flux isachieved, having positive effects on the mechanical performance of drivemotor 1.

A third approach to optimizing the efficiency of power motor 1 is todesign additional leg 130 with a smaller width d. Due to smaller width dof additional leg 130, it is possible to have a larger number of coilwindings on additional leg 130 with otherwise the same consumption ofmaterial. This approach also makes it possible to generate the samemagnetic field strength H with the same number of windings but a lowerconsumption of copper wire. The upper limit to be taken into accounthere is magnetic saturation occurring in a material beyond a certainfield strength. In the present case, additional leg 130 of stator 100 isoperated approximately in magnetic saturation.

FIG. 2 shows a top view of a configuration of stamped profiles forstator 100 from FIG. 1. This view shows the corresponding placement offirst nose 112 on first leg 110 with notch 122 on second leg 120. Firstleg 110 is continued in the same width as the integrally molded nose 112after engagement of second leg 120 via notch 122. This measure is notabsolutely necessary but would not cause a reduction in stamping wasteand thus may be used as a positive factor in managing the magneticfield. Second noses 124 are provided on the outside in the stampedprofile and thus cause a widening thereof, but this is accepted becauseof the great mechanical effect of a wider second air gap B.

A recess 102 is provided between first leg 110 and additional leg 130.This recess 102 makes it possible to place the stamped profiles oneinside the other despite the longer design of additional leg 130 in theform shown here and thus to reduce stamping waste.

FIG. 3 shows a top view of a second specific embodiment of a drive unitfor a hair cutting machine. For the sake of simplicity, tappet 160 andsupport 190 from FIG. 1 are not shown here. The specific embodimentshown in FIG. 3 differs from that shown in FIG. 1 essentially in thattwo additional legs 130 are provided. Armature 150 also has two recesses152, both of which are shaped as described in the first exemplaryembodiment. An exciter coil 140 is situated on each additional leg 130,exciter coils 140 being triggerable in synchronization for operation ofdrive motor 1. As shown in FIG. 1, first air gap section A is enlargedby a first nose 112 integrally molded on first leg 110, and second airgap section B is enlarged by a second nose 124 integrally molded on thesecond leg. Second leg 120 also has a notch 122 provided to correspondto first nose 112 in this specific embodiment. Due to the design ofstator 100 having two additional legs 130 and two exciter coils 140situated thereon, it is possible first of all to generate a greatermagnetic flux through two exciter coils 140 in stator 100 and at thesame time to enlarge the magnetically relevant gap area, which includeslateral air gap sections A, B and central air gap sections a, b as wellas sections c running parallel to the longitudinal axis of additionalleg 130 and thereby to optimize the mechanical performance of drivemotor 1.

FIG. 4 shows a top view of a configuration of stamped profiles for astator 100 as shown in FIG. 3. As in the configuration of stampedprofiles in FIG. 2, first nose 112 again engages in notch 122 and thusallows two stamped profiles to lie one inside the other. In theconfiguration shown in FIG. 4, one of two additional legs 130 comes tolie between first leg 110 and an additional leg 130 of the secondstamped profile, second additional leg 130 being situated between twoadditional legs 130 of the other stamped profile. To be able to designthe additional legs 130 to have a greater length, dimpled recesses maybe provided between the legs, allowing a compact configuration of thestamped profiles.

It should be recalled in particular that with the specific embodimentshown here, it is necessary to design first leg 110 and second leg 120of stator 100 to have a smaller width in order to allow theconfiguration of the stamped profiles shown in FIG. 4.

FIG. 5 shows a detail of the specific embodiment of FIG. 1, in which aspring bracket 180 connecting armature 150 to stator 100 is providedinstead of support 190. In this specific embodiment, it is advantageousin particular that drive motor 1 is premountable outside of a housing ofthe hair cutting machine and is then inserted as a complete module intothe housing. Corresponding slots 182 may be provided in armature 150 andstator 100 for fastening spring bracket 180, this spring bracket 180being pressed into the slots. This allows a particularly simpleassembly. In the exemplary embodiment shown here, stator 100 andarmature 150 have a rectangular molding 184 in which slots 182 areprovided. However, molding 184 may also be shaped in such a way that aslot running at an inclination is achieved.

In summary, it should be pointed out that several advantages areachievable through the specific embodiments presented here. Inparticular, optimization of the mechanical performance of the drivemotor is possible due to the novel design of the lateral air gapsections A, B as well as central air gap sections a, b andsupplementation thereof by parallel air gap sections c. In addition, itis possible to achieve a compact configuration of the stamped profilesand to minimize waste in stamping the individual sheet metal layers inmanufacturing drive motor 1 described here due to the correspondingplacement of first nose 112 with notch 122. It is also possible tooptimize the magnetic flux in the stator and to reduce copperconsumption for the windings of exciter coil 140 due to the design ofadditional leg 130 having a smaller width d.

List of Reference Numerals

1 Drive motor

100 Stator

102 Recess

110 First leg

112 First nose

120 Second leg

122 Notch

124 Second nose

130 Additional leg

140 Exciter coil

150 Armature

152 Recess

154 Section

156 Second end

158 First end

160 Tappet

180 Spring bracket

182 Slot

184 Molding

190 Support

192 Oscillating spring

194 Fastening bolt

A First lateral air gap section

B Second lateral air gap section

s Gap width

a First central air gap

b Second central air section

c Parallel air gap section

d Width

L Longitudinal axis

H Magnetic field strength

1. A drive unit for a hair cutting machine having a drive motor,comprising: a substantially U-shaped stator having a first leg and asecond leg and at least one additional leg, which is situated betweenthe first leg and the second leg; at least one exciter coil placeable onthe at least one additional leg; an armature, wherein lateral gapsections are formed between the first and second legs and the armature,and central air gap sections are formed between the additional leg andthe armature, the central air gap sections and the lateral air gapsections each running at an inclination with respect to a longitudinalaxis; a first nose which is provided at the end of the first leg andpoints away from the additional leg; and a notch, which is provided onthe second leg, points toward the additional leg and is placed tocorrespond to the first nose.
 2. The drive unit as recited in claim 1,further comprising: a second nose which is situated on the end of thesecond leg and points away from the additional leg.
 3. The drive unit asrecited in claim 1, wherein the armature has a recess in the area of theadditional leg, the recess being substantially triangular and having atleast one section which faces the armature and runs parallel to thelongitudinal axis.
 4. The drive unit as recited in claim 1, wherein theadditional leg has a length, at least one section of the additional legrunning parallel to its longitudinal axis and engaging in a recesssituated to correspond to the armature.
 5. The drive unit as recited inclaim 1, further comprising: a tappet situated on a first end of thearmature.
 6. The drive unit as recited in claim 1, wherein the armatureis mounted to allow vibration.
 7. The drive unit as recited in claim 1,wherein the stator and the armature are connected by a spring bracketwhich is placeable on a second end of the armature and on the stator. 8.The drive unit as recited in claim 1, wherein the second nose issituated on the leg of the stator associated with the second end of thearmature.
 9. The drive unit as recited in claim 1, wherein the statorhas inside radii at the transitions to the legs that counteract anincrease in a magnetic flux density.
 10. The drive unit as recited inclaim 1, the at least one additional leg is thinner than the first andsecond legs.
 11. The drive unit as recited in claim 1, wherein the atleast one additional leg is operated approximately in magneticsaturation at a given magnetic field strength.
 12. The drive unit asrecited in claim 1, the stator has a recess between the first leg andthe at least one additional leg.
 13. The drive unit as recited in claim1, wherein two additional legs aligned in parallel are provided.
 14. Aconfiguration of stamped profiles for a stator for a drive unit,comprising: a drive unit, including: a substantially U-shaped statorhaving a first leg and a second leg and at least one additional leg,which is situated between the first leg and the second leg; at least oneexciter coil placeable on the at least one additional leg; an armature,wherein lateral gap sections are formed between the first and secondlegs and the armature, and central air gap sections are formed betweenthe additional leg and the armature, the central air gap sections andthe lateral air gap sections each running at an inclination with respectto a longitudinal axis; a first nose which is provided at the end of thefirst leg and points away from the additional leg; and a notch, which isprovided on the second leg, points toward the additional leg and isplaced to correspond to the first nose, wherein two of the stampedprofiles are rotated by 180°, the configuration being such that thefirst nose of a stamped profile engages in the notch of the otherstamped profile.
 15. A hair cutting machine, comprising: a drive unit,including a substantially U-shaped stator having a first leg and asecond leg and at least one additional leg, which is situated betweenthe first leg and the second leg; at least one exciter coil placeable onthe at least one additional leg; an armature, wherein lateral gapsections are formed between the first and second legs and the armature,and central air gap sections are formed between the additional leg andthe armature, the central air gap sections and the lateral air gapsections each running at an inclination with respect to a longitudinalaxis; a first nose which is provided at the end of the first leg andpoints away from the additional leg; and a notch, which is provided onthe second leg, points toward the additional leg and is placed tocorrespond to the first nose.
 16. The hair cutting machine as recited inclaim 15, further comprising: a second nose which is situated on the endof the second leg and points away from the additional leg.
 17. The haircutting machine as recited in claim 15, wherein the armature has arecess in the area of the additional leg, the recess being substantiallytriangular and having at least one section which faces the armature andruns parallel to the longitudinal axis.
 18. The hair cutting machine asrecited in claim 15, wherein the additional leg has a length, at leastone section of the additional leg running parallel to its longitudinalaxis and engaging in a recess situated to correspond to the armature.19. The hair cutting machine as recited in claim 15, further comprising:a tappet situated on a first end of the armature.
 20. The hair cuttingmachine as recited in claim 15, wherein the armature is mounted to allowvibration.